1. Field of the Invention
The present invention relates generally to an apparatus for homogeneously distributing lights, and more particularly, to an apparatus for homogeneously distributing lights applied to a direct type backlight module.
2. Description of the Related Art
Large-scale liquid crystal display (LCD) is mainly applied to a notebook computer or an LCD monitor. Liquid crystal material does not emit light itself. Therefore an external light source is needed for displaying images. Because of a trend of light, thin, short and small styles of a light source of a backlight module, and a requirement for being applied to a large-scale panel, such as an LCD television (TV), the backlight module is not only supposed to have the above-mentioned advantages, but also have other advantages, such as high display luminance, broad visual angle, distinct image contrast and long life. Therefore, direct type backlight module, which is designed for solving the limitations of low luminance in lateral sides thereof and unhomogeneously distribution of the lights, when used in large-scale panels, takes full advantage of its high display luminance to apply direct type linear light source for homogeneously distributing the lights; converts the homogeneous lights into area lights; and imports the area lights to the illumination area.
General light source of direct type backlight module is cold cathode fluorescernt lamp (CCFL) or light emitting diode (LED). The CCFL has properties like high brightness, high efficiency and long life, and has a cylinder-shaped configuration which is easily coupled with light reflection components to form laminal lighting device. Therefore the CCFL has become the mainstream light emergence component. However, CCFLs are often arranged in a row and disposed at a bottom of an LCD panel, thereby the images displayed on the LCD are asymmetric in light intensity distribution because the diffusion angles of the scattered lights are usually too large, and the light emergence directions are usually disordered. Thus obvious profiles of the CCFLs are shown on the screen, which damage the quality of the images. Therefore, under the circumstance of direct type backlight module being applied, the larger of the dimension of the LCD panel and the greater of the number of the CCFLs are used, the more serious of the deficiency of black and white stripes shown on the screen occurs. The above mentioned problem is a main bottle-neck in the way of the development of the LCD display quality.
To solve the above mentioned problem, diffusion components and prisms are disposed between the CCFLs and the LCD panel to diffuse and then converge the lights. Therefore the lights emitted by the CCFLs are diffused, and then the diffusion angle is reduced for being efficiently coupled with the LCD panel, thereby homogeneously distributing the lights. However, the above design applies so many optical components as to not easy to be manufactured, and sharply increase the costs. Furthermore, the effect of homogeneously distributing the lights of the design is finite, and not the best solution to solve the problem.
Referring to FIG. 6, U.S. Pat. No. 6,280,063 discloses a multi-layer brightness enhancement article 60 for enhancing the on-axis luminance of a diffuse lighting device. The brightness enhancement article 60 comprises a base layer 61, a separate layer 62 plated on the a bottom of the base layer 61, and a microstructure layer 63 arranged on a side of the base layer 61 opposite to the separate layer 62. The separate layer 62 is used for diffusing the lights. The microstructure layer 63 is used for converging the diffused lights. By using the separate layer 62 and the microstructure layer 63, the lights are homogeneously distributing. However, different processes are required in this invention for respectively forming the separate layer 62 and the microstructure layer 63, thereby increasing the manufacture costs. Furthermore, the processes are complicated and not suitable for mass production, and the effect of homogeneously distributing the lights can not satisfy the images quality requirements of consumers.
Referring to FIG. 7, US Pub. No. 20020001055 discloses a backlight module structure 70, which applies resin particles to form a light diffusion layer 71. The light diffusion layer 71 diffuses the lights emitted by a backlight source 72 with wide-angle. A prism sheet 73 then converges the lights to achieve an effect of homogeneous diffusion. However, the backlight module structure 70 comprises so many components that leads to a complicated manufacture process and increases the manufacture costs. Furthermore, the homogeneous diffusion effect and the efficiency of the light utilization can not satisfy the market demands.
Additionally, conventional method also increases the number and the arrangement density of the CCFLs to solve the problems of unhomogeneously distributing the lights and of the profiles of the CCFLs being shown on the screen. However, the method greatly increases the manufacture costs. Furthermore, because of the configure limitation, if any one of the CCFLs failures, the whole row of CCFLs will be replaced with a new one. Under the circumstance of the number of the CCFLs being increased, the chance and frequency of CCFL failure and replace are correspondingly increased. Thus the service life of the whole LCD panel is shortened.
Thus an improved apparatus applied in the direct type backlight module for homogeneously distributing the lights, efficiently utilizing the light source, greatly lowering the manufacture costs and meeting the demands of the market is desired.